make tests work without VS2013 installed

Author: dsyme

tests/projects/Sample_VS2013_FSharp_Portable_Library_net45/Sample_VS2013_FSharp_Portable_Library_net45.fsproj

@@ -48,7 +48,7 @@
   <PropertyGroup>
     <MinimumVisualStudioVersion Condition="'$(MinimumVisualStudioVersion)' == ''">12</MinimumVisualStudioVersion>
   </PropertyGroup>
-  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\3.1\Framework\v4.0\Microsoft.Portable.FSharp.Targets" />
+  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\4.0\Framework\v4.0\Microsoft.Portable.FSharp.Targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">

tests/projects/Sample_VS2013_FSharp_Portable_Library_net451_adjusted_to_profile259/Sample_VS2013_FSharp_Portable_Library_net451.fsproj

@@ -48,7 +48,7 @@
   <PropertyGroup>
     <MinimumVisualStudioVersion Condition="'$(MinimumVisualStudioVersion)' == ''">12</MinimumVisualStudioVersion>
   </PropertyGroup>
-  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\3.1\Framework\v4.0\Microsoft.Portable.FSharp.Targets" />
+  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\4.0\Framework\v4.0\Microsoft.Portable.FSharp.Targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">

tests/projects/Sample_VS2013_FSharp_Portable_Library_net451_adjusted_to_profile78/Sample_VS2013_FSharp_Portable_Library_net451.fsproj

@@ -48,7 +48,7 @@
   <PropertyGroup>
     <MinimumVisualStudioVersion Condition="'$(MinimumVisualStudioVersion)' == ''">12</MinimumVisualStudioVersion>
   </PropertyGroup>
-  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\3.1\Framework\v4.0\Microsoft.Portable.FSharp.Targets" />
+  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\4.0\Framework\v4.0\Microsoft.Portable.FSharp.Targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">

tests/service/FsiTests.fs

@@ -151,7 +151,7 @@ let ``EvalExpression parse failure nothrow``() =
     |> shouldEqual 
           ["exception Operation could not be completed due to earlier error";
            "error 1,5 - 1,8; Unexpected keyword 'let' or 'use' in binding";
-           "error 1,1 - 1,4; The block following this 'let' is unfinished. Expect an expression."]
+           "error 1,1 - 1,4; The block following this 'let' is unfinished. Every code block is an expression and must have a result. 'let' cannot be the final code element in a block. Consider giving this block an explicit result."]
 
 [<Test>]
 let ``EvalInteraction typecheck failure``() = 

tests/service/data/sqlite-net-spike/sqlite-net-spike.fsproj

@@ -53,7 +53,7 @@
   <ItemGroup>
     <Compile Include="Program.fs" />
   </ItemGroup>
-  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\3.1\Framework\v4.0\Microsoft.FSharp.Targets" />
+  <Import Project="$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\4.0\Framework\v4.0\Microsoft.FSharp.Targets" />
   <Choose>
     <When Condition="$(TargetFrameworkIdentifier) == 'WindowsPhone' And $(TargetFrameworkVersion) == 'v8.0'">
       <PropertyGroup>